Applications – Kirchhoff’s Law

Kirchhoff’s law assists us in constructing complicated circuits, including a variety of electrical components that we encounter in our daily lives. It also aids in analysing any electrical circuit, such as determining how much current is flowing in different portions of an electrical circuit. This article discusses Kirchhoff’s current and voltage laws and their use in contemporary electrical appliances to compute the current flow and voltage drop in complicated circuits.

Two laws devised in 1845 are Kirchhoff’s Voltage Law (KVL) and Kirchhoff’s Current Law (KCL) that are still in use today. This set of laws is known as Kirchhoff’s circuit law. These laws are used to do circuit analysis. They aid in identifying the flow of current in various streams as they traverse the computer network.

Kirchhoff’s first law

It is also known as Kirchhoff’s Current Law (KCL) and it asserts that the “total current or node is precisely equal to the total current charge entering a junction or charge exiting the node, as no charge is lost at the node.” Kirchhoff’s Current Law (KCL) is a law that regulates the flow of current and charge in a circuit. In other words, the algebraic sum of all currents entering and departing a node must be zero.

Kirchhoff’s second law

Kirchhoff’s second law (also known as the loop law) applies the principle of conservation of energy in mathematics. Although the loop law is expressed as to potential energy rather than potential energy, the two concepts are connected. Remember that emf is defined as the potential difference between a source and a sink when no current flows. 

There are no alternative means of transferring energy into or out of a closed-loop, which means that whatever power is provided by emf must be converted into other forms by the devices in the loop. The potential changes in a primary series circuit loop. Kirchhoff’s second law demands that emf Ir + IR1 + IR2 = 0, implying that the emf equals the total IR (voltage) decrease in the loop when rearranged.

Uses of Kirchhoff’s law

It is used to determine how much current is flowing and how much voltage is being lost in various places of the intricate circuit.

It helps to detect the current flow direction in various circuit loops.

When it comes to understanding how energy passes via an electric circuit, Kirchhoff’s law may be pretty helpful.

How to apply Kirchhoff’s laws?

It is necessary to regard the currents leaving a junction as unfavourable in sign, whereas the currents entering a junction are taken as positive in sign when applying the KCL formulae.

i.e. Ir + IR1 + IR2 = 0,

We also ensure that we keep the same anticlockwise or clockwise orientation from where we started the loop while applying KVL. We account for all voltage decreases as negative and all voltage climbs as positive during the application KVL. This brings us back to the starting position when the total sum of all voltage drops equals one.

Sign conventions 

We account for all voltage decreases as negative and all voltage climbs as positive during the application KVL. 

It is usually positive in a loop when the potential difference or electromotive force increases from lower to higher levels.

A reduction in the potential difference or EMF from a higher to a lower value is always seen as negative in a loop.

If the direction of the looping is the same as the current flowing through the circuit, the voltage drop across the resistor is negative.

Examples of Kirchhoff’s law in daily life

Deserts are scorching because sand is gritty and black, making it a great heat conductor. According to Kirchhoff’s law, the nights will be cold since an absorber is also an emitter. As a result, the desert is scorching during the day and extremely cold at night.

Temperatures are higher and lower for black bags than white bags because they absorb more heat and release more energy when the temperature is lower than when the temperature is higher.

A person with dark cloth experiences more heat and cold than a person with white colour cloth because when the outside temperature is higher, the person with black cloth absorbs more heat. When the outside temperature is lower, the person with black cloth radiates more energy compared to a person with white cloth.

Kirchhoff’s law Limitations or Drawbacks

Kirchhoff’s law states that the magnetic field in the loop’s region stays constant throughout, which precludes the possibility of a change in magnetic flux and the formation of EMF in the circuit. In the case of high-frequency alternating current circuits, this might lead to a calculation error.

Kirchhoff was likewise unknown to the influence of the electric field created by the other circuit components on his calculations.

KCL or Kirchhoff‘s circuit law operates on the assumption that current only flows through conductors and wires. In High-Frequency circuits, parasitic capacitance can no longer be ignored. In some conditions, electricity may begin to flow through conductors or wires acting as transmission lines, resulting in an open circuit.

Points to remember about Kirchhoff’s law

KVL applies to any lumped network, regardless of its nature, whether it is unilateral or bilateral, active or passive, linear or nonlinear or any combination of these characteristics.

Distributed networks are exempt from the application of KVL. Because there is no resistance in a short circuit, the voltage drop across the circuit is zero.

KVL is committed to energy conservation at all times.

Because of the infinite resistance of the open circuit, the greatest amount of voltage appears across the circuit.

In a parallel path, the voltage remains constant, but in a series path, the voltage is divided.

Conclusion

Gustav Kirchhoff contributed to a greater knowledge of solving circuits and networks. It is stated in the first law of Kirchhoff that the charge entering a node or junction is equal to the total current or charge exiting in the node. It is based on the principle of conservation of charge. This is referred to as Kirchhoff’s law.